1. Field of the Invention
The invention concerns a dental composition and method for controlling tartar formation on teeth.
2. The Related Art
Baking soda, chemically known as sodium bicarbonate, has become a popular ingredient in dental compositions. A considerable body of literature describes sodium bicarbonate dentifrices. These include U.S. Pat. Nos. 3,935,305, 3,937,803, 3,937,321, 3,937,804, 3,943,240 and 4,160,022, all to Delaney et al assigned to the Colgate-Palmolive Company.
Further patents in this area include U.S. Pat. Nos. 4,547,362, 4,623,536 and 4,943,429, all to Winston et al, assigned to the Church & Dwight Company, which markets Arm & Hammer brand toothpaste.
Sodium bicarbonate toothpastes such as the Arm & Hammer brand have become commercially successful because of association of the featured ingredient with malodor reduction and antibacterial activity. Whether these perceived effects are real is subject to debate. However, there is evidence to suggest that baking soda does not have antitartar activity.
Oral compositions containing both sodium bicarbonate and a peroxide have been acclaimed by the dental profession, especially through the work of Keyes. See Keyes et al. "Periodontics and Oral Hygiene", January 1978, pages 51-56.
There is a storage stability problem in formulating the products containing the two key elements of the Keyes technology. Decomposition occurs unless unusual measures are taken to separate the components. A quite successful approach to the problem has involved physical segregation of the peroxide into a compartment separate from the bicarbonate. U.S. Pat. Nos. 4,849,213, 4,687,663 and 4,528,180, all to Schaeffer, disclose a package with a dual-compartment respectively storing a peroxide gel and a bicarbonate paste. A successful commercial product known as Mentadent.RTM. has utilized the dual-compartment package concept to provide consumers with a storage stable product. Technology utilized in this product is reported in U.S. Pat. Nos. 5,037,633 and 5,037,634, both to Williams et al. While this product has been found to have a modest level of antitartar activity, there remains room for significant improvement.
Zinc compounds, especially zinc citrate, have a long history of use as antitartar actives. In the United States, zinc citrate has been formulated into the Close-Up.RTM. and Aim.RTM. brand products by Chesebrough-Pond's. Typical of the zinc antiplaque and antitartar technology is that described in U.S. Pat. No. 4,022,880 (Vinson et al), 4,647,452 (Ritchey et al) and 5,104,644 (Douglas). While zinc-formulated toothpastes have clinically demonstrated tartar reduction performance, they are generally no more effective than the commercially more prevalent pyrophosphate based technology. Taste problems limit use of higher zinc levels which would be expected to improve performance. There have been no successful attempts to combine zinc salts with bicarbonate to achieve any stable products. Our own experiments have demonstrated that zinc salts rapidly decompose bicarbonate.
Accordingly, it is an object of the present invention to provide dental compositions with improved antitartar activity.
It is another object of the present invention to provide a dental composition incorporating sodium bicarbonate in a product that exhibits significant antitartar activity while being storage stable.
It is a still further objective of the present invention to provide a dental composition incorporating sodium bicarbonate that exhibits improved antitartar activity yet minimizes taste problems often associated with antitartar actives.
These and other objects of the present invention will become more readily apparent upon consideration of the more detailed description and Examples which follow.